Trimming is the subsequent process carried out after successful drawing process and prior to performing springback analysis. It allows the user to perform hole piercing and/or trimming operation on the drawn parts. It also allows the user to add hole or lancing to the drawing process to change the deformation degree. Trimming process consists of four basic pages such as General and Blank pages described in Section 8.2.4 , Forming.
This function allows the user to define single or multiple groups of lines. These lines are chosen to perform piercing, lancing and/or trimming operation illustrated in Figure 8.2.99.
Figure 8.2.99 Trimming process
GROUP LIST
Group List lists all defined group names of the current line. The user classifies these lines for ease of line management. If multiple line groups are defined, the latest line group is always highlighted in the interface as well as on the display screen.
ADD
Create new line group.
DELETE
Remove selected or current line group. The dialog box illustrated in Figure 8.2.100 is displayed prompting the user to confirm Delete operation.
Figure 8.2.100 Delete question dialog box
GROUP NAME
This function allows the user to modify the name of the current group. When creating groups, the user can specify a unique name for the new group. The user may click on Group button to modify the group name by typing the new name in the input data field of NAME, following by press ENTER key to complete the operation.
ATTRIBUTES
This function allows the user to define line type, trimming mode and direction, seed, gap, tolerance, etc. The user can select different line type for definition of different attributes.
TYPE
There are two types of line: Tool cut (2D) and Laser cut (3D), which correspond to 2D and 3D trimming respectively.
NOTE: The trimming direction of 2D line is determined according to the defined vector direction; and the trimming direction of 3D line is determined according to the normal direction of element.
MODE
There are three modes of 2D trimming: TRIMMING, HOLE and LANCING. For TRIMMING and HOLE, the user must select the closed curve. The user can classify these curves.
DIRECTION
Define trimming direction. Refer to the previous sections for description about defining direction.
TOLERANCE
Trimming tolerance is used to control the size of elements generated after trimming operation. If the value is zero, element size is not restricted; if the value is 0.5, the size of the newly generated element should at least be half of its parent element; if the value is 1, it is allowed to move the original node to the trim curve without generating new element after trimming. If the tolerance value is negative, the user only perform simple trimming, i.e. deleting the entire element while keeping the serrated boundary. The default tolerance is 0.25.
SEED
Any node on trimmed part after trimming operation can be defined as seed node.
GAP
Define the maximum gap between trim curve and mesh. If the value is greater than a specified gap, the corresponding segment of trim curve is disabled.
GEOMETRY
This function allows the user to translate, add and delete lines.
POSITION
Translate the selected trim curve. The user can input the translation value and click on the distance to be translated to complete the line translation. There are three input data fields corresponding to dx, dy and dz values under the current CS.
ADD
Allow the user to add one or more trim curves. Click ADD button to display the SELECT LINE dialog box. Refer to the previous sections for information on methods of selecting lines.
DELETE
Remove the selected lines. Select the lines and click DELETE button to display a dialog box illustrated in Figure 8.2.101.
OK: Confirm the selected line.
CANCEL: Abort the Delete operation.
Figure 8.2.101 Delete line question dialog box
This function allows the user to set parameters of refining mesh along trimming curves. The interface is illustrated in Figure 8.2.102.
REFINING MESHES
REFINING MESHES ALONG TRIMMING CURVES
Once this option is selected, the user is allowed to set parameters of refining mesh along trimming curves. If this option is not selected, the trimming operation does not consider such operation.
MAX. REFINEMENT LEVELS (IFADA): The default level is 3, i.e. an element can be refined into 16 elements.
MIN. REFINEMENT SIZE (SMIN): The allowable minimum refinement size. The default is 0.
Figure 8.2.102 Trimming control parameters interface